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From: Ben Greear <greearb@candelatech.com>
To: Johannes Berg <johannes@sipsolutions.net>,
	"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: How many null-data probes on connection loss?
Date: Thu, 27 Sep 2018 08:32:23 -0700	[thread overview]
Message-ID: <a409f0b7-5a91-1add-484d-588a554f0cd4@candelatech.com> (raw)
In-Reply-To: <1538032363.14416.2.camel@sipsolutions.net>



On 09/27/2018 12:12 AM, Johannes Berg wrote:
> On Wed, 2018-09-26 at 15:21 -0700, Ben Greear wrote:
>>
>> Now only 4 retries per frame, but it seems mac80211 is all 5 of its
>> null-data probes within a few miliseconds.  Is that expected, or should
>> there be a bit more pause between each of the probe requests to better
>> weather periodic network glitches?
>
> Hmm. That's a good point, but it seems we've never considered this
> before. This must be a consequence of retrying immediately on lost ACK,
> but I guess I could see that delaying it for a little bit would make
> sense.
>
> We do delay it if there's no reliable ACK reporting, IIRC, but if we
> know it failed for sure ...
>
> It seems though that if there's some noise or so on the channel you
> wouldn't be transmitting, so what kind of "network glitches" might
> affect this? AP going away unexpectedly for some time?

I am thinking that if the 'timeout' is 500ms, and the number of probes is 2
(the default values), then it should probe at 0ms, and at 250ms, and then finally
fail at 500ms if nothing was received.  In otherwords, X probes, x/timeout apart.

I should have a patch to make it work more like I think it should work
later today for discussion.

Thanks,
Ben


-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

  reply	other threads:[~2018-09-27 15:32 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-25 23:12 How many null-data probes on connection loss? Ben Greear
2018-09-26  8:38 ` Johannes Berg
2018-09-26 18:04   ` Ben Greear
2018-09-26 18:26     ` Johannes Berg
2018-09-26 18:47       ` Ben Greear
2018-09-26 18:48         ` Johannes Berg
2018-09-26 18:53           ` Ben Greear
2018-09-26 22:21           ` Ben Greear
2018-09-27  7:12             ` Johannes Berg
2018-09-27 15:32               ` Ben Greear [this message]
2018-09-28  7:19                 ` Johannes Berg
2018-09-28 15:14                   ` Ben Greear

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